The Most Rev. Dr. John Hamilton (3 February 1512 – 6 April 1571), Scottish prelate and politician, was an illegitimate son of James Hamilton, 1st Earl of Arran.
At a very early age he became a monk and Abbot of Paisley, and after studying in Paris he returned to Scotland, where he soon rose to a position of power and influence under his half-brother, the regent James Hamilton, 2nd Earl of Arran. He was made Keeper of the Privy Seal of Scotland in 1543 and bishop of Dunkeld two years later; in 1546 he followed Cardinal Beaton as Archbishop of St Andrews, and about the same time he became treasurer of the kingdom.
In 1553 the Italian physician Gerolamo Cardano cured him of a disease that had left him speechless and was thought incurable. The diplomat Thomas Randolph recorded the "merry tales" rumoured about his methods still current in Edinburgh nine years later. Cardano himself wrote that the Archbishop had been short of breath for ten years, and after the cure was effected by his assistant, he was paid 1,400 gold crowns. While the Archbishop was unwell, his brother was persuaded to give up the Regency of Scotland to Mary of Guise.
He made vigorous efforts to stay the growth of Protestantism, but with one or two exceptions persecution was not the policy of Archbishop Hamilton, and in the interests of the Roman Catholic religion a catechism called Hamilton's Catechism (published with an introduction by TG Law in 1884) was drawn up and printed, possibly at his instigation.